1. Field of the Invention
This invention relates to structures comprising either a composite or a material. The composite is made from a filler comprising particulate matter or fibers, filaments or yarn in combination with an inorganic binder composition optionally containing refractory materials. For the purpose of the present invention non-woven fabrics manufactured using the inorganic binder composition as a binder (versus a surface coating) will be classified as composites. The inorganic binder composition may be present in a small amount but sufficient to bind the filler material to itself, the inorganic binder composition also being present up to an amount sufficient to act as a matrix for the filler. The inorganic binder composition in this respect may comprise from 1 to 99% by weight of the structure on a dry weight basis. The composite is then formed by shaping, either with or without pressure, after which water is removed from the inorganic binder composition and the binder is cured. The inorganic binder composition imparts flame, heat and high temperature resistance to the composite.
This invention also relates to inorganic binder composition coated filaments, fibers or yarn and a structure comprising materials made therefrom. Materials for the purpose of this invention include fabrics whether woven or knitted and braided, cordage or roving and any material made from fibers or filaments such as yarn. Non-woven fabrics that we held together mechanically e.g. needle punched fabrics will be classified as materials for the purpose of the present invention. More particularly, the present invention relates to filaments, fibers or yarn having a coating of an inorganic binder compostion and, optionally, refractory materials formed thereon and materials made therefrom. This invention especially relates to filaments, fibers or yarns of natural or synthetic materials or mixtures thereof having formed thereon a coating of an inorganic binder composition optionally containing refractory materials after which water is removed from the binder and the binder is cured. The coating imparts flame, heat, and high temperature resistance to the fibers, filaments or yarn and the materials made therefrom.
In making the materials, the fibers, filaments or yarn are first coated with the inorganic binder composition and then formed into a material. The structure comprising the composite is distinguished from the structure comprising the materials of this invention in that the composite is formed by adhesively binding fillers e.g. particulate matter or fibers, filaments or yarn to one another and the material is made from completely coated fibers, filaments or yarns that have the inorganic binder composition applied and cured first and then are formed into a material without the inorganic binder composition being employed to adhere the fibers, filaments or yarns to one another. The completely coated fibers, filaments, or yarns, however, can be made into a composite whereby at least two refractory binder coatings are applied; at least one to envelop the fiber, filament, or yarn and at least one to bond the fiber, filament or yarn to one another.
2. Description of the Prior Art
Ceramics and/or glass fibers have been used herebefore to prepare high temperature electrical insulating tape. U.S. Pat. No. 4,358,500 discloses refractory coated insulating compositions wherein the refractory coating, comprising refractory materials and an inorganic bonding agent, is formed on the surface and, necessarily, the interstices of a porous base fabric, such as a knitted fiberglass fabric. In the presence of extreme temperatures and heat, the refractory materials fuse into the softened surface of the base fabric, enabling it to withstand intense heat, flame impingement, flame abrasion and elevated temperatures well beyond the normal temperature limitations of the fabric. The resulting fabric structure will have ceramic qualities and will not soften, melt, drip or lose its insultating properties.
Commonly assigned U.S. Pat. Nos. 4,375,493, 4,429,999 and 4,396,661 relate to multi-functional fabric compositions having a refractory coating on one side of the base fabric and a different coating providing a different function on the other side, i.e., the '999 patent--a vapor barrier coating, the '493 patent--a conductive coating and the '661 patent--a dielectric coating.
The inorganic bonding agent disclosed in U.S. Pat. No. 4,358,500 is prepared from colloidal silica, monoaluminum phosphate (MAP) and aluminium chlorohydrate (ACH) by adding the MAP and ACH separately to the colloidal silica which acts as a liquid moderator. Although the compositions containing the inorganic bonding agent of U.S. Pat. No. 4,358,500 may be exposed to high temperatures, no products of combustion in the form of smoke or fumes are produced as with other prior art coated fabrics. Further, the refractory coated compositions prepared with the inorganic bonding agent proved superior to inorganic coatings available for use on fabrics or paper substrates. The latter inorganic coatings could be damaged by water. They could be wet by water and the water could solvate the coating to the point of causing the inorganic coating to dissociate itself from the substrate. Although other binders, such as the acrylics, inhibited this wetting action, they would burn off when subjected to flame and high temperature. The refractory coated substrates disclosed in the '500 patent, on the other hand, are not wetted by water and are not subject to the solvation action of water as are other inorganic coatings. However, despite these advantages, the refractory coated compositions of the '500 patent exhibit a very undesirable feature. This refractory coating must be applied to a porous fabric so that the coating will be placed in the interstices of the fabric. This is necessary to achieve the formation of the refractory coating on this fabric. However, this requires the use of a larger quantity of the refractory coating when preparing these compositions to the extent that the coating in many instances constitutes about 50% of the overall weight of the impregnated base fabric. The result of all this is that when this coated fabric is flexed, the bond of the refractory coating to the substrate is disrupted and some particles may be released to the surface resulting in "dusting" of the coating. This, of course, is highly undesirable despite the very desirable features of flame and high temperature resistance which are exhibited by these refractory coated compositions.
Additionally, when fabrics, whether woven, knitted or nonwoven are impregnated with a coating such as a inorganic binder composition, the intersection of the fibers, filaments or yarns from which the fabrics are made, may not receive any coating or only a minimal amount of coating and as such comprise points or areas on the fibers, filaments or yarn where heat degredation and other degredation of the fabric can be initiated.
In addition to their use as insulating tape for electrical wires and cables, these materials were attempted to be employed as high temperature gas filters. Since the inorganic binder composition is formed on the porous knitted or woven fabric, the size of the individual openings is difficult to control with any degree of precision and attempts to achieve this control have not been successful.
Natural and synthetic fibrous materials are employed in such composites (as that term is defined herein) as paper, thermal insulation and the like where the fibrous materials are provided in short lengths or continuous filaments disposed in a random or regular fashion. Binders (also known as bonding agents) of various types are often employed to retain the materials in a fixed position and, in some instances, to provide a certain degree of rigidity (mechanical integrity) to the composition. Fiber glass and mineral wool insulation in the form of batts, blankets or pipe insulation are examples of these products. Asbestos and glass fiber papers for electrical insulation are other examples. Wood particle molded roof shingles are another. Woven fabrics made from natural fibers or synthetic organic fibers optionally containing an organic coating are examples of materials of this type (as that term is defined herein). Various resins, polymers and/or other organic compounds are employed as binders in these structures. Acrylic resins are often employed in asbestos and glass paper while formaldehyde type resins (e.g. urea-formaldehyde and phenol formaldehyde resins) are used to prepare semi-rigid pipe insulation of fiberglass. Exposure of these composites or materials to extremely high temperatures can cause the binder or filler, e.g. fiber or particulate, to decompose producing smoke and fumes which may prove harmful to persons in the vicinity. In other circumstances, the binder may produce flames upon exposure to such high temperatures causing a potentially dangerous situation.
It is therefore an object of this invention to provide a novel composition of matter and structure comprising a composite or material employing a inorganic binder composition, optionally containing a refractory material.
It is also an object of this invention to provide a novel composition of matter comprising a filler, and an inorganic binder composition, and a novel composite made therefrom by forming the filler and composition followed by drying the composition where the inorganic binder composition functions to bind the filler to itself or may act as a matrix for the filler.
It is also an object of this invention to provide fibers, fillers, or yarns that are completely enveloped in an inorganic binder composition.
It is an object of the invention to provide a material where the fiber, filament on yarn from which it is made is completely enveloped with an inorganic binder composition before the material is manufactured.
It is a further object of this invention to provide a novel composition comprising fibers, filaments or yarn coated with an inorganic binder composition.
It is an object of this invention to enable the manufacture of a high temperature resistant fabric having precisely controlled apertures.
It is an object of this invention to provide composites or materials, e.g. fabrics containing randomly or regularly oriented fibrous materials, which can be exposed to flame or high temperatures without the production of noxious fumes and/or flames that prior art composites or materials have produced heretofore.
It is an object of this invention to provide an improved fabric having an inorganic bonding agent (binder) composition which provides an intimate bond between the inorganic binder composition and the fibrous surface of the fabric so that the coating will not dissociate itself from the fabric by flexure of the coated composition.
It is another object of this invention to provide a fabric coated with an inorganic binder composition which will not exhibit "dusting" of the inorganic binder composition in use.